Human-machine interfaces that are used to translate human movements to machine movements are used in myriad industries. For example, some aircraft flight control systems include a human-machine interface in the form of one or more control sticks. The flight control system, in response to input forces supplied to the control stick from the pilot, controls the movements of various aircraft flight control surfaces. No matter the particular end-use system, the human-machine interface preferably includes some type of haptic feedback mechanism back through the interface to the interface operator. In some implementations, the haptic feedback mechanisms are active mechanisms that include one or more electrically controlled motors to supply force feedback to the human-machine interface.
Although unlikely, it is postulated that the electrically controlled motor, or other electrical or mechanical portions of the feedback mechanism, could become inoperable. Thus, in addition to the active feedback mechanism, many human-machine interfaces are also implemented with one or more passive feedback mechanisms, such as one or more springs. These backup mechanisms, while useful, can present certain drawbacks. For example, the forces exhibited by each passive mechanism may need to be incorporated into and/or compensated for by the active feedback mechanism. This can make implementation of the active feedback mechanism potentially more complex and costly.